Antibacterial effectiveness of diluted preparations of intracanal medicaments used in regenerative endodontic treatment on dentin infected by bacterial biofilm: An ex vivo investigation

Abstract

Background: Conventional drug mixtures used in regenerative endodontic procedures have a
toxic effect and no consensus has been reached about their best composition and concentration.
Therefore, the aim of this study was to determine minimum inhibitory concentration (MIC), minimum
bactericidal concentration (MBC), and minimum biofilm inhibitory concentration (MBIC) of the
antimicrobial preparations and to compare their antimicrobial efficacy on bovine dentin infected
by Enterococcus faecalis.
Materials and Methods: For this original ex vivo investigation, prepared concentrations (MIC,
MBC, and MBIC) of triple antibiotic paste (TAP), double antibiotic paste (DAP), modified triple
antibiotic paste (MTAP)‑1, MTAP2, co‑amoxiclav, and calcium hydroxide (CH) were added to the
prepared bovine dentin blocks (which incubated in E. faecalis suspension previously) and incubated
for 3 days. The samples were subsequently prepared for culture and CFU counts. Statistical analysis
of data was carried out using one‑way analysis of variance and post hoc tests. The statistical power
was set at P < 0.05.
Results: All medicament groups significantly showed an antimicrobial efficacy compared with
negative control (without antibiotic) (P < 0.001). TAP, DAP, co‑amoxiclav, and CH (at its MBC value)
were significantly capable of eliminating E. faecalis biofilm and showed no significant difference in
comparison with positive control (complete biofilm removal) (P < 0.05).
Conclusion: TAP, DAP, co‑amoxiclav, and CH (at its MBC value) could effectively eliminate biofilm
bacteria on the dentin surface. Antimicrobial efficacy of other medicaments containing cefaclor or
clindamycin was limited.
Key Words: Biofilms, Enterococcus faecalis, regenerative endodontics